Electric discharge apparatus



Sept. 16, 1946. A. M. SKELLETT ELECTRIC DISCHARGE APPARATUS Filed Feb.5, 1941 II/Z/ 1L ll ll J 1 18 H 23 L? r W2 2? mm: w.

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ELECTRON! ENTER /E LE C TRODE l4 POTENTIAL or ELECTRODE /4 AVERAGEPOTEN- TML OF ELECTRODE l4 ELECTRONS ENTER ELECTRODE l5 MTENTML OFELECTRODE [5 AVERAGE POTENTIAL OF ELECTRODE l5 ELECTRONS EN7ER ELECTRODEl6 Pan-mm or ELECTRODE /5 AVERAGE PO TEN T/AL POTENTIAL AVERAGEPOTENTIAL OF ne'er/e005 l7 ELECTRONS LEAVE ELECTRODE IT AND ENTERCOLLECTOR ELECTRODE l2 lNVENTOR A. M. SKELLETTY ATTORNEY Patented Sept.10, 194G ELECTRIC DISCHARGE APPARATUS Albert M. Skellett, Madison, N.J., assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Application February 5, 1941, Serial No.377,458

13 Claims.

This invention relates to electric discharge apparatus and moreparticularly to apparatus for and a method of electronically generatinghigh potentials.

One general object of this invention is to enable the facile andefiicient generation of high potentials.

In one illustrative embodiment of this invention, an electron stream isprojected through a series of cylindrical electrodes mounted in coaxialand end-to-end relation, the cylindrical electrodes being so constructedand energized that in passing through each of these electrodes, theelectrons in the stream obtain an increase in their potential energywithout substantial net change in their kinetic energy. The stream,after its passage through the series of cylindrical electrodes, impingesupon a target or collector electrode to which it transfers its energywhereby the target or collector electrode becomes of a high negativepotential relative to the source of the electron stream.

The invention and the various features thereof will be understood moreclearly and fully from the following detailed description with referenceto the accompanying drawing, in which:

Fig. 1 is a diagrammatic view of electron discharge apparatusillustrative of one embodiment of this invention;

Fig. 2 is a diagram illustrating the relation between the potentials ofthe various electrodes in the apparatus shown on Fig. 1 and time of theelectron stream as it traverses the device;

Fig. 3 is an elevational view partly in section of electron dischargeapparatus illustrative of another embodiment of this invention; and

Fig. 4 is a fragmentary view showing a modification of the embodiment ofthis invention illustrated in Fig. 1.

Referring now to the drawing, the apparatus illustrated in Fig. 1comprises an elongated evacuated enclosing vessel [0, a cathode II atone end of the vessel, a cup-shaped target or collector electrode H2 atthe other end of the Vessel and in alignment with the cathode II, and anaccelerating electrode or grid [3 adjacent the cathode H. Mountedbetween the cathode H and the target or collector electrode l2 and incoaxial, equally spaced end-to-end relation are a plurality of identicalcylindrical electrodes l4 to IT, inclusive.

The cathode H is energized by a suitable source, such as a battery l8,to cause copious emission of electrons therefrom, the electrons beingaccelerated away from the cathode by the accelerating electrode or gridl3, which is maintained at a relatively low positive potential, forexample, of the order of volts, with respect to the cathode, as by abattery I9. The target or collector electrode l2 and the cylindricalelectrodes M to I! are connected to one another through suitableresistances 20, as shown. The cylindrical electrodes are connected intwo groups, l4, I6 and I5, ll, through suitable condensers 2|, the two.groups being connected to opposite ends of the secondary winding 22 of atransformer T, the primary winding of which is connected to anoscillator 23 for producing a sinusoidal potential. The mid-point of thesecondary winding 22 and the accelerating electrode or grid I3 may begrounded as shown.

As shown in Fig. 2, the alternating current potentials of successivecylindrical electrodes are substantially equal and degrees out of phase.Thus, for example, when the alternating current potential of theelectrodes [4 and I6 is decreasing the alternating current potential ofthe electrodes l5 and I! is increasing. The length of the cylindricalelectrodes and the frequency of the oscillator 23 are so relatedtogether with the accelerating potential on the grid l3 that the time ofelectron travel from one gap between two successive cylindricalelectrodes to the next gap is equal to one-half period of thealternating potential. This relation may be expressed mathematically aswhere F is the frequency of the oscillator in cycles per second, V isthe accelerating potential in volts, and L is the distance between thecenters of successive cylindrical electrodes in centimeters.

At the beginning of operation of the device, the average potentials ofthe cylindrical and collector electrodes are zero. The electronsemanating from the cathode H are accelerated by the acceleratingelectrode or grid l3 and enter the first cylindrical electrode l4 whenthe potential of the electrode I4 is substantially the same as that ofthe grid l3. When the electrons are inside of the electrode M, thepotential of the electrode l4 swings negative, as shown in Fig. 2. Atthe same time, as pointed out above, the potential of the secondcylindrical electrode is increasing so that when the electrons havetraversed the first cylindrical electrode I4 and reach the gap betweenthe electrodes [4 and I5, these two electrodes-are at the samepotential. Consequently, the electron velocity at this gap is the sameas the velocity of the electrons entering the first cylindricalelectrode 44 and the kinetic energy of the electrons in passing throughthe electrode Hi remains unchanged. However, as the electrons passthrough the electrode l4, their potential energy is increased, thenecessary power for the work done being supplied by the oscillator 23.

In a like manner, as the electrons pass through each of the ucceedingcylindrical electrodes they obtain an increase in their potential energywithout change in their kinetic energy. Hence, at each cylindricalelectrode the electrons are carried further negative, as illustrated inFig. 2. The electrons emerging from the final cylindrical electrode llare travelling at their initial velocity and flow to the target orcollector electrode I2 where their energ is expended and, as a result,the target or collector electrode is charged to or maintained at a highnegative direct current potential with respect to the cathode II. Themagnitude of this potential will be dependent upon the number ofcylindrical electrodes employed, and the maximum value thereof, ingeneral, is given by the relation where P is the potential, 71 is thenumber of cylindrical electrodes, E is the R. M. S. value of theoscillating potential of the cylindrical electrodes and V is theaccelerating potential on the grid l3.

When the electrons arrive at the target or collector electrode I2 andcharge it negatively as described above, current passes back to groundthrough the resistances so that the average potentials upon thecylindrical electrodes are adjusted whereby the electrodes I4 to I! aremade successively more negative than the next preceding electrode andthe potentials of these electrodes are as illustrated in Fig. 2.

The apparatus may be utilized to generate high potentials or for otherpurposes. For example, it may be utilized as a detector. If a radiofrequency input, for example in the megacycle range, is supplied by theoscillator 23, the direct current potential of the target or collectorelectrode l2 will be proportional to the magnitude of the radiofrequency input. If the radio frequency input is modulated, the directcurrent potential of the target or collector electrodes will vary inaccordance with the modulating signal so that detection withamplification is obtained.

It will be understood, of course, that the condensers 2| should be ofsuch capacitance that the 1 several radio frequenc circuits are tuned tothe operating frequency whereby high efficiency operation is realized.

The apparatus may be utilized also to generate X-rays. For example, inone form suitable for this purpose illustrated in Fig. 4, the electrodei2 is provided with a central aperture 29 through which the electronstream passes. The stream then impinges upon the target 30, connected toground as shown. In traversing the space between the electrodes l2 and30, the electrons passing through the aperture 29 have their potentialenergy converted into kinetic energy and, hence, will generate X-rayswhen the impinge uponthe target 30.

In the embodiment of the invention illustrated in Fig. 3, the severalcylindrical electrodes are mounted in coaxial end-to-end relation andsupported by annular dished metallic members sealed to and extendingthrough the wall. of the vitreous enclosing vessel l0, and the severalcylindrical electrodes are electrically associated by coupled annularcavity resonators 26 each of which includes a pair of the dishedmetallic members 25 spaced at their peripheries and connected as shown.Each cavity resonator is of a diameter substantially equal to one wavelength of the operating frequenc of the apparatus and the severalresonators are so constructed that the alternating potentials ofsuccessive cylindrical electrodes are degrees out of phase, as in theapparatus disclosed in Fig. l. The first cavity resonator, that is, theone nearest the cathode ll is energized through a coaxial line 21coupled to an oscillator, the resonators being tuned to the frequency ofthe oscillator. The operation of the apparatus illustrated in Fig. 3 isbasically the same as that of the apparatus shown in Fig. l anddescribed heretofore. The target or collector electrode l2 may have ashield terminal 28 connected thereto as shown- The members 25 of thevarious resonators may be provided with apertures, not shown, to varythe coupling between the resonators.

In both embodiments of the invention illus trated and described eitherelectrostatic or magnetic focussing of the electron stream may beemployed. For example, if the cylindrical electrodes are so constructedand arranged that the potential curves of adjacent electrodes. overlapto a small extent, the gaps between adjacent electrodes will act asdouble positive electronic lenses and the electrons focussed along theaxis thereby. Magnetic focussing may be obtained by suitable magnetsexterior to the enclosing vessel it.

Although in the embodiments of the invention shown and described,electron streams are utilized, the invention may be practiced also bycausing a. stream of ions to flow through the series of cylindricalelectrodes energized in. the same manner as in the embodiments of theinvention described hereinabove. When ion streams are employed, theoperating frequencies in most cases will be in the kilocycle range. The.ion streams may be focussed in. the same manner as the electron streams.

Also, although the invention has been described with particularreference to devices of the high vacuum type, i. e., devices wherein theenclosing vessel is evacuated to. a high degree, it may be embodied alsoin gaseous discharge devices. For example, the enclosing vessel IE1 inthe apparatus shown in Figs. 1 and 3 may have therein a filling Of asuitable gas at such pressure that the ion current is less than theelectron current. During operation of such device, both the ions andelectrons travel in the same direction, that is toward the target orcollector electrode l2, and impinge upon the target or collectorelectrode.

It will be understood that the specific embodiments of the inventionshown and described are but illustrative and that various modificationsmay be made therein without departing from the scope and spirit of thisinvention as defined in the appended claims.

What is claimed is:

1. The method of generating a potential which comprises producing astream of charged particles, accelerating said particles, projecting theaccelerated particles toward a target, maintaining in the spacetraversed by said particles in flowing toward said target anelectrostatic field increasing toward said target, impressing uponadjacent regions of said space an alternating electric field, thealternating field in each region being substantially 180 degrees out ofphase with the alternating field in the adjacent region, and collectingsaid particles at said target.

2. The method of generating a potential which comprises producingastream of electrons, accelerating the electron stream, projecting theaccelerated electron stream toward a target, producing in a series ofsuccessive regions along the path along which the stream is projectedalternating electric fields such that the alternatin fieldln each regionis substantially 180 degrees out of phase with the alternating field inthe adjacent region, maintaining in each of said regions anelectrostatic field component greater negatively than in the nextpreceding region, whereby in traversing said series of regions saidelectrons gain an increase in their potential energy without substantialchange in their kinetic energy, and collecting said electrons after theyhave traversed said series of regions.

3. The method of generating a potential which comprises producing astream of charged particles, projecting said stream through a timegradient of electric potential, subjecting said particles whiletraversing said time gradient to a direct current electrostatic fieldincreasing in the direction of projection of said stream to maintain thevelocity of said particles substantially constant, and then collectingsaid particles.

4. The method of generating a potential which comprises producing astream of electrons, projecting said stream through an electrostaticfield of increasing negative potential in the direction of projection ofsaid stream, maintaining in the region of said field traversed by'saidstream a time gradient of electric potential related to saidelectrostatic field to maintain the velocity of said electronssubstantially constant, and collecting said electrons after they havetraversed said field.

5. Electric discharge apparatus comprising a target electrode, meansprojecting a stream of charged particles toward said target electrode,and means for increasing the potential energy of saidparticles in saidstream in their travel to said target electrode while maintaining thevelocity of said stream substantially constant, said last meansincluding electrodes and energizing means therefor for producing a timegradient of electric potential through which said stream' asses inflowing to said target electrode.

6. Electron discharge apparatus comprising a cathode, means foraccelerating the electrons emanating from said cathode, a targetelectrode for receiving the electrons, and means including F spacedelectrodes between said cathode and said target electrode and radiofrequency energizing means therefor for increasin the potential energyof said electrons in their travel to said target electrode withoutsubstantially altering the velocity thereof.

7. Electric discharge apparatus comprising a collector electrode, asource of charged particles, means for accelerating said articles towardsaid collector electrode, a pair of coaxial cylindrical electrodesmounted in end-to-end relation between said source and said collectorelectrode, means for increasing the energy of said particles in passingthrough said cylindrical electrodes including a source impressing aradio frequency potential between said coaxial electrodes, resistancemeans connecting said coaxial electrodes to one another and to saidaccelerating means, and an additional resistance means directlyconnected between said collector electrode and the cathode, anaccelerating electrode in cooperative relation with said cathode, meansmaintaining said electrode at a positive potential with respect to saidcathode, a collector electrode, a pair of coaxial cylindrical electrodesmounted in endto-end relation between said accelerating and collectorelectrodes, resistances connecting said coaxial electrodes to oneanother and to said accelerating electrode, an additional resistanceconnecting said collector electrod to the cylindrical electrode nearestthereto, and means for impressing a radio frequency potential betweensaid coaxial electrodes.

9. Electric discharge apparatus comprising a collector electrode, twogroups of cylindrical coaxial electrodes mounted in end-to-end relationand in alignment with said collector electrode, the electrodes of onegroup being mounted in alternate relation with the electrodes of theother group, means for projecting a stream of charged particles throughsaid coaxial electrodes toward said cellector electrode, means'resistively connecting each of said coaxial electrodes to the ne tsucceeding electrode, and a source of high frequency energy impressing aradio frequency potential between said coaxial electrodes such that thepotential of one group of said coaxial electrodes is substantiallydegrees out of phase with the potential of said other group ofelectrodes.

10. Electron discharge apparatus comprising means for producing a streamof electrical particles, a target electrode for receiving said stream, aplurality of coaxial cylindrical electrodes mounted in end-to-endrelation between said means and said target electrode, means foraccelerating said stream toward the coaxial electrodes, and means forimpressing a high frequency potential between one group of alternatecoaxial electrodes and the other of said electrodes, said coaxialelectrodes being spaced so that the distance between centers ofsuccessive coaxial electrodes is where L is said distance, V is theaccelerating potential due to said accelerating means and F is thefrequency of said high frequency potential.

11. Electron discharge apparatus comprising a cathode, a collectorelectrode in alignment with said cathode, an accelerating electrodeadjacent said cathode, means maintaining said accelerating electrode ata positive potential with respect to said cathode, two groups ofcylindrical electrodes mounted alternately and in coaxial endto-endrelation between said accelerating and collector electrodes, and meansfor impressing a high frequency potential between said groups ofelectrodes, each of said cylindrical electrodes having an efiectivelength equal to where V is the potential of said accelerating electrodeand F is the frequency of said high frequency potential.

12. Electron discharge apparatus comprising an enclosing vessel havingan ionizable filling therein, a cathode and a target electrode withinsaid vessel, means for accelerating electrons emanating from saidcathode toward said target electrode, a pair of cylindrical electrodesmounted in end-to-end relation. between said cathode and said targetelectrode, resistance means of substantial magnitude connecting saidcylindrical and target electrodes. to one another, and means forimpressing a high frequency potential between said cylindricalelectrodes.

13. Electric discharge apparatus comprising an apertured electrode,means for projecting a stream of charged particles toward said aperturedelectrode, a target electrode facing the face of said aperturedelectrode remote from the face toward which said stream is directed, andmeans for increasing the potential energy of said particles in theirtrave1 to said apertured electrode while maintaining their velocitysubstantially constant, said last means including a series of electrodesbetween said first means and said apertured electrode and energizingmeans therefor producing a time gradient of electric potential throughwhich said stream passes in flowing 10 toward said apertured electrode.

ALBERT M. SKELLETT.

